Analysis by: Rika Joi Gregorio
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

  TECHNICAL DETAILS

File Size: 447,923 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Apr 2013

Arrival Details

This backdoor arrives as an attachment to email messages spammed by other malware/grayware or malicious users.

Installation

This backdoor adds the following folders:

  • %User Temp%\hhx

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops the following files:

  • %User Temp%\2.pdf
  • %User Temp%\hhx\hha.dll

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It drops and executes the following files:

  • %User Temp%\hhx\hhc.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

Autostart Technique

This backdoor registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Credential Manager Command Line Utility
ImagePath = "%User Temp%\hhx\hhc.exe"

Other System Modifications

This backdoor adds the following registry keys:

HKEY_CLASSES_ROOT\FAST

HKEY_CURRENT_USER\Software\WinRAR SFX

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Credential Manager Command Line Utility

It adds the following registry entries:

HKEY_CLASSES_ROOT\FAST
CLSID = "{random}"

HKEY_CURRENT_USER\Software\WinRAR SFX
%User Temp% = "%User Temp%"

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://www.{BLOCKED}er.flower-show.org:443/update

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 9.852.05
FIRST VSAPI PATTERN DATE: 12 Apr 2013
VSAPI OPR PATTERN File: 9.853.00
VSAPI OPR PATTERN Date: 13 Apr 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Delete this registry key

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_CLASSES_ROOT
    • FAST
  • In HKEY_CURRENT_USER\Software
    • WinRAR SFX
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • Credential Manager Command Line Utility

Step 4

Search and delete this folder

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\hhx

Step 5

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\2.pdf

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_PLUGX.DMI. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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